Control circuit



Oct. 10, 1944. H. CARLETON 2,359,747

CONTROL CIRCUIT Filed March 20, 1945 IN V EN TOR. HENRY CARLETON HIS ATTORNEY Patented Oct. 10, 1944 UNITED STATES PATENT OFFICE CONTROL CIRCUIT- Henry Carleton, Roekville, Md. Application March 20, 1943, Serial No. 479,895 6 Claims. (Cl. 315-229) (Granted under the act of March 3, 1883, as amended'April 30. 1928: 370 0. G. 757).

-This invention is. in control circuits. It may also be termed a switch, or a switching means; and, as such, it is characterized by great precision and freedom from arcing.

The invention is an improvement on the standard parallel-control thyratron circuit, the nature of which is well known. Such circuits have heretofore required two separate switches, each governing a source of voltage for one of the tubes. In accordance with the disclosure herein, one switch is eliminated, and control is effected with one switch only and one source of control voltage.

One of the objects of the present invention is, therefore, to provide a quick-acting circuit including a thyratron tube the firing of which causes the controlled current to flow, and novel means for interrupting the flow of current.

Another object is to provide a thyratron control circuit with a single-pole, single-throw, switch, or the equivalent, the switch being adapted to produce both ignition and extinction of the current carrying tube.

Other objects will appear from a reading of the following specification and claims.

The single figure of the drawing is a schematic wiring diagram of the circuit of my invention, with the tube heating means indicated but not shown in full.

Referring to the drawing, i represents a load device, which will be assumed to be a magnetic clutch. Tube H is a thyratron, and this tube carries the clutch current. Tube l2 also is a thyratron, and this may be called the control tube.

One tube is a so-called positive grid thyratron, and one is a negative grid thyratron. In the embodiment shown, tube H is negative, and I2 is positive. In the description to follow, 110 volts will be applied to the plates of both tubes. ,For the purpose of explanation, it will be assumed that, under such conditions of plate bias, tube l I will fire unless its grid bias be maintained below zero. Positive tube l2, on the other hand, will not fire without approximately 3.25 volts on its grid. Tubes with various combinations of characteristics may be used.

The critical grid voltage of tube I2 is fixed by means of a biasing battery I3 located between the cathode and screen grid of the tube.

It and I6 are input terminals for a 110 volt direct current, the application of which to the magnetic clutch is to be controlled by the circuit. The 110 volt line also supplies anode voltage for tubes H and l2. I6 is a fuse which is inserted part of the figure,

' vary with the requirements of the circuit. In

the circuit described, resistors 2| and 22 are of I the order of 1000 ohms, and 23 and 24 are of the order of 4000 ohms.

The current limiting resistor 25 in the grid circuit of tub I! may be about .1 megohm.

When switch 28 is open (as shown), and with a 10 volt grid battery 20, a positive voltage of something more than 3.25 will be applied to the grid of tube I2, and this tube will fire. A voltage similar in value but opposite in polarity will be applied to the grid of thyratron' I I, and this tube will remain out.

As thyratron l2 conducts, condenser 30 will charge, the polarity being such that the left terminal thereof is negative.

If switch 26 should now be closed, the voltage on the control grids of both thyratrons will be brought to zero, tube II will fire, and condenser 30 will discharge through it, thereby efiectively putting a negative voltage on the anode of tube II. If the plate voltage is maintained below fir-' ing voltage long enough. for the tube to deionize.

thyratron ll extinguished.

When tube ll trolled current will retain control, tube 12 being ignites, the operating or conwill be applied to the magnetic clutch I0. At the same time, condenser 30 is charged, but at a. polarity opposite to that mentioned earlier. The time lapse between the closing of switch 26 and actuation of the clutch is only the ionization time of tube II.

If switch 28 be again opened, thyratron l2 will be ignited, and tube H will be extinguished by the action of condenser 30. At the same time, the magnetic clutch will discharge through condenser 3l and resistor 32.

The above description is in specific terms. My invention is not to be considered, however, as being limited to the described circuit, but includes those modifications thereof which fall properly within the scope of the appended claims.

The invention herein described and claimed may be manufactured and/or used by or for the Government of the United States of America without the payment 01' any royalty thereon or therefor.

I claim:

1. A circuit including a positive grid thyratron and a negative grid thyratron, means dependent upon the firing of neither one of said thyratrons for extinguishing the other of said thyratrons, a source of voltage having a positive pole for supplying positive grid voltage for the positive grid thyratron, and a negative pole for supplying negative grid voltage for the negative grid thyratron, a high resistance connection across said source, and a low resistance connection including a switch across said source, whereby with the switch in one position said positive grid thyratron only will be biased for ignition and with the switch in another position said negative grid thyratron only will be biased for ignition.

2. In a thyratron parallel control circuit, a thyratron for carrying the current to be controlled, a control tube, a source of direct current anode voltage, one of said tubes being adapted to fire at zero grid bias and the other at a different grid bias, a source of biasing voltage for the grids, and a switch having an open and a closed position associated with the grids and said source of biasing voltage, whereby with the switch in one position zero bias will be applied to the grids of both tubes to cause one oi them to fire, and with the switch in the other position voltages of opposite polarity will be applied to the grids of both tubes to cause the other tube only to fire.

3. In a control circuit, a positive grid thyratron tube adapted to fire with a predetermined positive grid-bias, a negative grid thyratron tube requiring a predetermined negative grid bias to prevent its firing, a source of voltage having a positive pole for supplying positive grid voltage suflicient to fire the first mentioned tube, and a negative pole for supplying negative grid voltage sufiicient to prevent firing oi the second mentioned tube, and means including a switch providing a low resistance connection across said source,

4. In a control circuit, a positive grid thyratron tube adapted to fire with a predetermined positive grid bias, 9. negative grid thyratron tube requiring a predetermined negative grid bias to prevent its firing, a battery having a positive pole and a negative pole a high resistance connection across said poles adapted to supply positive voltage sufficient to fire the first mentioned tube and negative voltage sufilcient to prevent firing oi the second mentioned tube, and means including a switch providing a low resistance connection across said poles.

5. In a control circuit, a positive grid thyratron tube adapted to fire with a predetermined positive grid bias, ,a negative grid thyratron tube requiring a predetermined negative grid bias to prevent its firing, means dependent upon the firing of one of said tubes for extinguishing the other of said tubes, a battery having a positive pole and a negative pole and adapted to supply positive voltage sufficient to fire the first mentioned tube and negative voltage sufllcient to prevent firing ot the second mentioned tube, means connecting the positive pole of the battery to the grid or the first mentioned thyratron, means connecting the negative pole to the grid of the second mentioned thyratron, and means including a switch providing when closed a low resistance connection between said poles, whereby with the switch in its open position the first mentioned thyratron only will fire, and with the switch closed the second mentioned thyratron only will fire.

6. A circuit including a positive grid thyratron tube and a negative grid thyratron tube, means dependent upon the firing of one of said tubes for extinguishing the other. of said tubes, a direct currentisource of anode voltage for both or said tubes, a source of voltage having a negative pole for supplying negative grid voltage for preventing ignition or the negative grid thyratron, and a positive pole for supplying positive grid voltage for igniting the positive grid thyratron, a singlepole single-throw switch connected to the grids and source of grid bias, whereby with the switch in one position the positive grid thyratron will be biased-ior'ignition and will fire, the negative grid thyratron being bi'a'sed'to prevent-it from firing, and with the switch in the other position, the negative grid thyratron will be biased to tire and will fire, and the positive grid thyratron will be biased not to fire and will be extinguished.

HENRY CARLE'ION.

CERTIFICATE OF CORRECTION.

'Patent No. 2,359,747. October 10, 1944.

HENRY CARLETI'ON' It is hereby certified that error appears in the printed specification of the atove numbered patent requiring correction as follows: Page 2., first column, line 2, for the word "neither" read eitherand that the said Letters Patent should be read with this correction therein that the same may conform to the record -of the case inthe Patent Office.

Signed and sealed this 2.6th'day of December, A. D. 1944.

Leslie :Frazer (Seal) Acting Commie sioner of Patents. 

